Methods for acquiring planar view stem images of device structures

ABSTRACT

A method of preparing a sample that includes milling an initial deep lamella within a wafer using a focused ion beam. The initial deep lamella includes at least one internal structure within an upper portion of the initial deep lamella. The method further includes lifting the initial deep lamella out of the wafer, placing the initial deep lamella on an upper surface of the wafer on a lateral side of the initial lamella, milling a planar shallow lamella out of a portion of the initial deep lamella and the wafer beneath the initial deep lamella to include at least substantially an entire length of the at least one internal structure of the initial deep lamella, lifting the planar shallow lamella out of the wafer, and placing the planar shallow lamella on a carbon grid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application Ser. No. 62/650,529, filed Mar. 30, 2018,the disclosure of which is hereby incorporated herein in its entirety bythis reference. This application is also a continuation-in-part of U.S.patent application Ser. No. 15/984,581, filed May 21, 2018, thedisclosure of which is hereby incorporated herein in its entirety bythis reference.

TECHNICAL FIELD

This disclosure relates generally to methods of making lamellae, totransmission electron microscope imaging (“TEM”), and to scanningtransmission electron microscope (“STEM”) imaging. More specifically,this disclosure relates to methods for acquiring a planar TEM or STEMimage of internal structures of a device such as a semiconductor deviceor a microelectromechanical system (MEMS) device.

BACKGROUND

Thin samples are conventionally cut (e.g., milled) from bulk samplematerial when determining a quality of microstructures formed on or in asemiconductor or other material. The samples are typically less thanabout 100 nm thick. Some techniques of forming lamellae are referred toas “lift-out” techniques. These techniques use focused ion beams to cutthe sample (e.g., lamella) from a substrate or bulk sample. Suchtechniques can be useful in analyzing the results of processes used inthe fabrication of integrated circuits. Some techniques extract a samplesufficiently thin for use directly in a transmission electronmicroscope; other techniques extract a “chunk” or larger sample thatrequires additional thinning before observation. In addition, these“lift-out” specimens may also be directly analyzed by other analyticaltools, other than TEM.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed understanding of the present disclosure, reference shouldbe made to the following detailed description, taken in conjunction withthe accompanying drawings, in which like elements have generally beendesignated with like numerals, and wherein:

FIG. 1 is a schematic depiction of a dual beam system suitable forperforming methods according to one or more embodiments of the presentdisclosure;

FIGS. 2A-2N illustrate acts of a process for preparing a sample of asemiconductor device for TEM and/or STEM imaging according to one ormore embodiments of the present disclosure;

FIG. 3 is an image of a sample of a semiconductor device according toone or more embodiments of the present disclosure;

FIGS. 4A-4E illustrate another process for preparing a sample of asemiconductor device for TEM and/or STEM imaging according to one ormore embodiments of the present disclosure;

FIG. 5 shows a front view of a planar lamella prepared via one or moreof the processes described herein;

FIGS. 6A-6J illustrate acts of a process for preparing a sample of asemiconductor device for TEM and/or STEM imaging according to one ormore embodiments of the present disclosure;

FIG. 7 is an image of a sample of a semiconductor device according toone or more embodiments of the present disclosure;

FIGS. 8A-8D illustrate another process for preparing a sample of asemiconductor device for TEM and/or STEM imaging according to one ormore embodiments of the present disclosure; and

FIG. 9 shows a front view of a planar shallow lamella prepared via oneor more of the processes described herein.

DETAILED DESCRIPTION

The illustrations presented herein are not actual views of any dual beamsystem, lamella, or any component thereof, but are merely idealizedrepresentations, which are employed to describe embodiments of thepresent invention.

As used herein, the singular forms following “a,” “an,” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise.

As used herein, the term “may” with respect to a material, structure,feature, or method act indicates that such is contemplated for use inimplementation of an embodiment of the disclosure, and such term is usedin preference to the more restrictive term “is” so as to avoid anyimplication that other compatible materials, structures, features, andmethods usable in combination therewith should or must be excluded.

As used herein, any relational term, such as “first,” “second,” “top,”“bottom,” “upper,” “lower,” etc., is used for clarity and convenience inunderstanding the disclosure and accompanying drawings, and does notconnote or depend on any specific preference or order, except where thecontext clearly indicates otherwise. For example, these terms may referto orientations of elements of a dual beam system, wafer, and/or lamellain conventional orientations. Furthermore, these terms may refer toorientations of elements of a dual beam system, wafer, and/or lamella asillustrated in the drawings.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone skilled in the art would understand that the given parameter,property, or condition is met with a small degree of variance, such aswithin acceptable manufacturing tolerances. By way of example, dependingon the particular parameter, property, or condition that issubstantially met, the parameter, property, or condition may be at least90.0% met, at least 95.0% met, at least 99.0% met, or even at least99.9% met.

As used herein, the term “about” used in reference to a given parameteris inclusive of the stated value and has the meaning dictated by thecontext (e.g., it includes the degree of error associated withmeasurement of the given parameter, as well as variations resulting frommanufacturing tolerances, etc.).

As used herein, the phrases “a planar STEM image,” “a planar TEM image,”“a planar STEM view,” and “a planar TEM view,” and any derivativephrases may refer to a view of internal structures of a semiconductordevice (e.g., a wafer) or of MEMS structures of a substrate that depictsthe internal structures as if viewed from a plane parallel to an uppersurface of the semiconductor device.

As used herein, the terms “wafer” and “substrate” mean and includematerials upon which and in which structures including featuredimensions of micrometer and nanometer are partially or completelyfabricated. Such terms include conventional semiconductor (e.g.,silicon) wafers, as well as bulk substrates of semiconductor and othermaterials. Such structures may include, for example, integratedcircuitry (active and passive), MEMS devices, and combinations thereof.

Semiconductor manufacturing, including the fabrication of integratedcircuits, may include the use of photolithography, among otherprocesses. A semiconductor substrate (e.g., a silicon wafer) on whichcircuits are being formed is typically coated with a material, such as aphotoresist, that changes solubility when exposed to radiation. Alithography tool, such as a mask or reticle, is typically positionedbetween a radiation source and the semiconductor substrate and casts ashadow to control that areas of the substrate that are exposed toradiation from the radiation source. After the exposure to theradiation, the photoresist is removed from either the exposed or theunexposed areas of the wafer, leaving a patterned layer of photoresiston the wafer that may protect portions of the wafer surface during anysubsequent etching or diffusion processes while selectively exposingother portions for treatment. Similar techniques are employed in thefabrication of MEMS devices.

The photolithography process allows multiple integrated circuit devices,referred to as “dice” or “chips,” or MEMS devices, to be formed on eachwafer or other substrate. The wafer is often then cut up, or“singulated,” into individual segments, each segment including a singleintegrated circuit device (i.e., die) or MEMS device. Ultimately, thesestructures are conventionally subjected to additional operations andpackaged.

During the manufacturing process, variations in exposure and focusrequire that the patterns developed by lithographic processes becontinually monitored or measured to determine if the dimensions andlocations of the patterns are within acceptable ranges. The importanceof such monitoring, often referred to as process control, increasesconsiderably as pattern sizes become smaller, especially as minimumfeature sizes approach the limits of resolution available by thelithographic process. In order to achieve ever-higher device density,smaller and smaller feature sizes are required. This may include thewidth and spacing, also termed “pitch,” of interconnecting metallizationlines, spacing and diameter of contact holes and vias, and the surfacegeometry such as corners and edges of various features. As features onthe wafer are three-dimensional structures, a complete characterizationshould describe not just a surface dimension, such as the top width of aline or trench, but a complete three-dimensional profile of the feature.Process engineers must be able to accurately measure various criticaldimensions (“CD”) of such surface features to fine tune the fabricationprocess and to assure a desired device geometry.

Conventionally, CD measurements are made using instruments such as ascanning electron microscope (“SEM”). In a SEM, a primary electron beamis focused to a fine spot that scans the surface to be observed.Secondary electrons are emitted from the surface as it is impacted bythe primary beam. The secondary electrons are detected, and an image isformed, with the brightness at each point of the image being determinedby the number of secondary electrons detected when the beam impacts acorresponding spot on the surface. As features continue to get smallerand smaller, however, there comes a point where the features to bemeasured are too small for the resolution provided by an ordinary SEM.

In a scanning transmission electron microscope (STEM), a primaryelectron beam is focused to a fine spot, and the spot is scanned acrossthe sample surface. Electrons that are transmitted through the substrateare collected by an electron detector on the far side of the sample, andthe intensity of each point on the image corresponds to the number ofelectrons collected as the primary beam impacts a corresponding point onthe surface.

Transmission electron microscopes (TEMs) allow observers to seeextremely small features, on the order of nanometers. In contrast toSEMs, which only image the surface of a material, TEMs allows theadditional capability to analyze the internal structure of a sample. Ina TEM, a broad beam impacts the sample and electrons that aretransmitted through the sample are focused to form an image of thesample. The sample must be sufficiently thin to allow many of theelectrons in the primary beam to travel though the sample and exit onthe opposite site. Accordingly, samples are typically less than 100 nmthick.

As semiconductor geometries continue to shrink, manufacturersincreasingly rely on TEMs for monitoring the process, analyzing defects,and investigating interface layer morphology. The term “TEM” as usedherein refers to a TEM or a STEM, and references to preparing a samplefor a TEM are to be understood to also include preparing a sample forviewing on an STEM. Because a sample must be very thin for viewing withtransmission electron microscopy (whether TEM or STEM), preparation of ausable sample can be delicate, time-consuming work.

Thin TEM samples cut from a bulk sample material are known as“lamellae.” Lamellae are typically less than 100 nm thick, but for someapplications a lamella must be considerably thinner. With advancedsemiconductor fabrication processes at 30 nm and below, a lamella mayneed to be less than 20 nm in thickness in order to avoid overlap amongsmall scale structures.

Some techniques of forming lamellae are referred to as “lift-out”techniques. These techniques use focused ion beams in a vacuum chamberto cut the sample (e.g., lamella) from a substrate or bulk samplewithout destroying or damaging surrounding parts of the substrate. Suchtechniques are useful in analyzing the results of processes used in thefabrication of integrated circuits, as well as materials general to thephysical or biological sciences. These techniques can be used to analyzesamples. Some techniques extract a sample sufficiently thin for usedirectly in a TEM; other techniques extract a “chunk” or large samplethat requires additional thinning before observation. In addition, these“lift-out” specimens may also be directly analyzed by other analyticaltools, other than TEM. Techniques where the sample is extracted from thesubstrate within the focused ion beam (“FIB”) system vacuum chamber arecommonly referred to as “in-situ” techniques; sample removal outside thevacuum chamber (as when the entire wafer is transferred to another toolfor sample removal) are call “ex-situ” techniques.

Some embodiments of the present disclosure include a process ofpreparing a sample of semiconductor material (e.g., a wafer) havingintegrated circuitry formed over an active surface thereof to provide aplanar STEM and/or TEM image of the internal structures of thesemiconductor material. The process may include loading a wafer into thedual beam system to create (e.g., ion mill) an initial lamella (referredto hereinafter as the “initial lamella”) from the wafer. For instance,the dual beam system may mill the initial lamella via any of the methodsknown in the art. In addition, the process may include creating a nestnear a milling site of the initial lamella. The nest may be sized andshaped to receive an upper portion (i.e., a rectangular portion) of theinitial lamella. In some embodiments, the nest may include a carbonmaterial. The process may further include lifting and placing theinitial lamella on an upper surface of the wafer with a probe. Forinstance, the process may include lifting and placing the initiallamella with a lamella extraction station. In one or more embodiments,the initial lamella may be disposed flat on the upper surface of thewafer. The process may include placing the initial lamella on the uppersurface of the wafer at a location proximate to the nest and thensliding the initial lamella along the upper surface of the wafer intothe nest. The process may further include milling a second lamella(referred to hereinafter as the “planar lamella”) to include at least aportion of an upper portion of the initial lamella. Additionally, theprocess may include lifting the planar lamella from the second millingsite and placing the planar lamella on an amorphous carbon grid forimaging with a TEM and/or STEM.

In view of the foregoing, because the initial lamella is milled, placedon its side on the upper surface of the wafer, milled again as a portionof the planar lamella, and then placed on the amorphous grid, when theplanar lamella and, specifically, the portion of the planar lamellaincluding the upper portion of the initial lamella is imaged, a planarcross-section view of the initial lamella is achieved that is notachievable utilizing conventional operations of the dual beam system.For instance, the planar lamella includes a first cross-sectional viewof internal structures of the wafer within the portion of the planarlamella not comprising the initial lamella, and a second cross-sectionalview of the internal structures that is orthogonal to the firstcross-sectional view within the portion of the planar lamella comprisingthe initial lamella. The first cross-sectional view may include a viewdepicting internal structures as if viewed from a plane orthogonal tothe upper surface of the wafer, and the second cross-section view mayinclude a view depicting internal structures as if viewed from a planeparallel to the upper surface of the wafer. Typically, at best,conventional methods only achieve the first cross-sectional view.

FIG. 1 is a schematic depiction of a dual beam system 110 that may beutilized to perform acts described herein in regard to FIGS. 2A-2N. Insome embodiments, the dual beam system 110 may be used to perform theacts with a vertically mounted SEM (e.g., a longitudinal axis of the SEMis oriented in a vertical direction) column and a focused ion beam(“FIB”) column mounted at an angle of approximately 45 degrees from avertical longitudinal axis of the vertically mounted SEM. In someembodiments, the dual beam system 110 may comprise a commerciallyavailable dual beam system from, for example, Thermo Fisher ScientificCompany, Hillsboro, Oreg. For instance, the dual beam system 110 maycomprise the Thermo Fisher Scientific ExSolve DualBeam™ system. Asanother example, the dual beam system 110 may include the dual beamsystem 110 described in U.S. Patent Publication No. 2017/0250055A1, toKeady et al., filed May 15, 2017. While an example of a dual beam system110 is described below, the disclosure is not limited and the processesdescribed herein may be implemented with other dual beam systems and/orion beam systems.

In some embodiments, the dual beam system 110 may include a scanningelectron microscope 141 and a power supply and control unit 145. Inoperation, the electron microscope 141 may emit an electron beam 143from a cathode 152 by applying voltage between the cathode 152 and ananode 154. In one or more embodiments, the electron beam 143 may befocused to a relatively fine spot via a condensing lens 156 and anobjective lens 158. Furthermore, the electron beam 143 may be scannedtwo-dimensionally on a specimen via a deflection coil 160. The powersupply and control unit 145 may control operation of the condensing lens156, the objective lens 158, and the deflection coil 160.

In one or more embodiments, the dual beam system 110 may further includea lower chamber 126 housing a substrate 122, a movable X-Y stage 125,and one or more TEM sample holders 124. The substrate 122 may bedisposed on the movable X-Y stage 125. In some embodiments, thesubstrate 122 may include one or more of a semiconductor device, awafer, and a sample. The one or more TEM sample holders 124 may bedisposed on (e.g., supported by) the movable X-Y stage 125. In operationand is described below, lamellae may be milled within the substrate 122and may be extracted from the substrate 122 and moved to a TEM sampleholder 124. Furthermore, in some embodiments, the movable X-Y stage 125may be movable in a horizontal plane (X and Y axes) and vertically alonga vertical axis (Z axis). Additionally, the movable X-Y stage 125, whichmay also be characterized as a support or a support surface, may betilted and rotated about the Z axis. In some embodiments, a separate TEMsample stage (not shown) can be used. Such a TEM sample stage will alsobe moveable in the X, Y, and Z axes. In one or more embodiments, thedual beam system 110 may include a door 161 that may be opened forinserting a substrate 122 onto X-Y stage 125. The door 161 may beinterlocked so that the door 161 cannot be opened if the dual beamsystem 110 is under vacuum.

In operation, the dual beam system 110 may focus the electron beam 143onto the substrate 122. When electrons in the electron beam 143 strike(e.g., hit) the substrate 122, secondary electrons are emitted, as isknown in the art. The secondary electrons may be detected by a secondaryelectron detector 140, as is discussed in greater detail below. Forinstance, a STEM detector 162 may be located beneath a TEM sample holder124 and the X-Y stage 125 and may collect electrons that are transmittedthrough a sample mounted on the TEM sample holder 124.

The dual beam system 110 may also include a focused ion beam (“FIB”)system 111. The FIB system 111 may include an ion column 112, an upperneck portion 113, and a focusing column 116. The ion column 112 mayinclude an ion source 114, an extraction electrode 115, a focusingelement 117, deflection elements 120, and a focused ion beam 118. Theion source 114 of the ion column 112 and the focusing column 116 may beat least partially disposed within the upper neck portion 113 of the FIBsystem 111. As noted above, a longitudinal axis of the FIB system 111(i.e., the focusing column 116) is oriented at a 45-degree angle fromthe longitudinal axis of the scanning electron microscope 141. Inoperation, the focused ion beam 118 passes from the ion source 114through the focusing column 116 and between the electrostatic deflectionelements 120 toward the substrate 122 disposed on the movable X-Y stage125 within the lower chamber 126 of the dual beam system 110. When theion beam 118 strikes the substrate 122, material of the substrate 122may be sputtered and physically ejected, from the substrate 122. As willbe discussed in greater detail below, in some embodiments, the ion beam118 may be utilized to prepare lamellae from the substrate 122.Alternatively, the ion beam 118 can be utilized to decompose a precursorgas to deposit a material, as is described in greater detail below.

The dual beam system 110 may include an ion pump 168 for evacuating oneor more portions of the FIB system 111. Additionally, the dual beamsystem 110 may include a turbomolecular and mechanical pumping system130 operably coupled to and controlled by a vacuum controller 132 forevacuating the lower chamber 126. In some embodiments, theturbomolecular and mechanical pumping system 130 under the direction ofthe control of a vacuum controller 132 may provide a vacuum of betweenapproximately 1×10−7 Torr (1.3×10−7 mbar) and 5×10−4 Torr (6×10−4 mbar)within the lower chamber 126. As will be understood by one of ordinaryskill in the art, if an etch assisting, an etch retarding gas, or adeposition precursor gas is used, the lower chamber's 126 backgroundpressure may rise to about 1×10−5 Torr (1.3×10−5 mbar).

The dual beam system 110 may further include a high voltage power supply134 that provides an appropriate acceleration voltage to electrodes inion beam focusing column 116 for energizing and focusing the ion beam118. The high voltage power supply 134 may be connected to a liquidmetal ion source 114 and to appropriate electrodes in the ion beamfocusing column 116 for forming an approximately 1 keV to 60 keV ionbeam 118 and directing the ion beam 118 toward the substrate 122.

Additionally, the dual beam system 110 may include a deflectioncontroller and amplifier 136 and a pattern generator 138. The deflectioncontroller and amplifier 136 may be operably coupled to the patterngenerator 138. Furthermore, the deflection controller and amplifier 136may be operably coupled to the deflection elements 120. As such, the ionbeam 118 may be controlled manually and/or automatically to trace out acorresponding pattern on an upper surface 204 of substrate 122. In someembodiments, the dual beam system 110 may operate the deflectioncontroller and amplifier 136 in accordance with a prescribed patternprovided by the pattern generator 138. In some embodiments, thedeflection elements 120 may be disposed before the final lens along adirection in which the ion beam 118 is directed, as is known in the art.As is understood in the art, in some embodiments, beam blankingelectrodes within ion beam focusing column 116 may cause the ion beam118 to impact onto a blanking aperture instead of substrate 122 when ablanking controller applies a blanking voltage to the blankingelectrode.

The liquid metal ion source 114 may provide a metal ion beam of gallium.The liquid metal ion source 114 may be capable of being focused into asub one-tenth micrometer wide beam at the substrate 122 for eithermodifying the substrate 122 by ion milling, enhanced etch, materialdeposition, or for the purpose of imaging the substrate 122.

In some embodiments, the dual beam system 110 may further include acharged particle detector 140. In one or more embodiments, the chargedparticle detector 140 may include an Everhart Thornley or multi-channelplate and may be used for detecting secondary ion or electron emission.The charged particle detector 140 may be connected to a video circuit142, which supplies drive signals to video monitor 144 and receivesdeflection signals from a system controller 119. The orientation andlocation of the charged particle detector 140 within the lower chamber126 may vary in different embodiments. For example, a charged particledetector 140 may be coaxial with the ion beam 118 and may include a holefor allowing the ion beam 118 to pass therethrough. In otherembodiments, secondary particles can be collected through a final lensand then diverted off axis for collection.

Additionally, the dual beam system 110 includes a micromanipulator 147for precisely moving object within a vacuum chamber within the lowerchamber 126. In some embodiments, the micromanipulator 147 may includean AutoProbe 200™ from Omniprobe, Inc., Dallas, Tex., or Model MM3A fromKleindiek Nanotechnik, Reutlingen, Germany. In additional embodiments,the micromanipulator 147 may form at least a portion of a TEMlink™(i.e., a TEMLink™ TEM Lamella Extraction Station). In furtherembodiments, the micromanipulator 147 may include a TFS EZlift. In oneor more embodiments, the micromanipulator 147 may include one or moreprecision electric motors 148 positioned outside the vacuum chamber ofthe lower chamber 126 to provide X, Y, Z, and theta control of a portion149 positioned within the vacuum chamber of the lower chamber 126. Themicromanipulator 147 may be fitted with different end effectors formanipulating small objects. For instance, in some embodiments, themicromanipulator 147 may include an end effector include a thin probe150 (e.g., a thin glass probe). In other embodiments, themicromanipulator 147 may be separate from a TEMlink™, which may be usedin conjunction with the dual beam system 110 to manipulate samples(e.g., lamellae) formed from the substrate 122.

The dual beam system 110 may further include a gas delivery system 146extending into the lower chamber 126. The dual beam system 110 mayutilize the gas delivery system 146 to introduce and direct a gaseousvapor toward the substrate 122. For instance, the gas delivery system146 may include any of the gas delivery systems described in U.S. Pat.No. 5,851,413, to Casella et al., issued on Dec. 22, 1998. In additionalembodiments, the gas delivery system 146 may include any of the gasdelivery systems described in U.S. Pat. No. 5,435,850, to Rasmussen,issued Jun. 25, 1995. In some embodiments, the dual beam system 110 mayutilize the gas delivery system 146 to deliver iodine to the substrate122 to enhance etching. In additional embodiments, the dual beam system110 may utilize the gas delivery system 146 to deliver a metal organiccompound or metal on the substrate 122. As will be described in greaterdetail below, the dual beam system 110 may utilize the gas deliverysystem 146 to deposit a carbon nest 226 on the wafer 200 and/or fiducialmarkers 210 on the wafer 200.

The system controller 119 may control the operations of the variousparts of the dual beam system 110. For instance, via the systemcontroller 119, an operator may cause the ion beam 118 and/or theelectron beam 143 to be scanned in a desired manner through commandsentered into a conventional user interface. For instance, an operatormay utilize the system controller 119, user interface, and video monitor144 (e.g., display) to input one or more parameters of a procedure(e.g., recipe) to perform with the dual beam system 110. Alternatively,the system controller 119 may control the dual beam system 110 inaccordance with programmed instructions. In some embodiments, the dualbeam system 110 incorporates image recognition software. For instance,the dual beam system 110 may include software commercially availablefrom Cognex Corporation, Natick, Mass., to automatically identifyregions of interest. Additionally, system controller 119 can cause thedual beam system 110 to manually or automatically extract samples inaccordance with the embodiments described herein. For example, thesystem controller 119 may automatically locate similar features onsemiconductor wafers including multiple devices, and take samples ofthose features on different (or the same) devices.

FIGS. 2A-2N show a process 201 through which a planar view STEM imagemay be acquired utilizing the dual beam system 110 (e.g., the ThermoFisher Scientific ExSolve DualBeam™) described above in regard toFIG. 1. In other words, the process 201 may be utilized to achieve aSTEM image that depicts internal structures of a wafer as if viewed froma plane parallel to an upper surface of the wafer. The process 201 mayinclude loading a wafer 200 into the dual beam system 110 to create(e.g., ion mill) an initial lamella 218 (referred to hereinafter as the“initial lamella 218”) from the wafer 200. In some embodiments, thewafer 200 may include an upper portion 202 proximate to an upper surface204 of the wafer 200 and a bulk silicon base portion 206 beneath theupper portion 202. As will be understood in the art, the upper portion202 may include features (e.g., internal structures) of interest, andSTEM images of those features may be desirable to determine a quality ofthe wafer 200, defects in the wafer 200, etc. As a non-limiting example,the wafer 200 may include an upper portion 202 comprising an activesurface comprising integrated circuitry in the form of semiconductordevices as known in the art.

Referring to FIG. 2A, in some embodiments, when creating the initiallamella 218, the dual beam system 110 may deposit a protective layer 208of a material such as tungsten over a region of interest 207 on theupper surface 204 of the wafer 200 (i.e., where the initial lamella 218will be milled) using the electron beam or the ion beam depositionmethods described above in regard to FIG. 1. For instance, the dual beamsystem 110 may deposit the protective layer 208 utilizing either theelectron beam 143 or the focused ion beam 118. In some embodiments, thedual beam system 110 may deposit the protective layer 208 utilizing thegas delivery system 146 in any of the manners for depositing materialsdescribed above in regard to FIG. 1. In other embodiments, the process201 may not include depositing a protective layer 208. In other words,not every embodiment described herein requires depositing of aprotective layer 208. Additionally, the process 201 may includedepositing one or more fiducial markers 210 to identify a milling siteof the initial lamella 218 and to assist in orienting the focused ionbeam 118 of the dual beam system 110 during a milling operation. In someembodiments, an operator of the dual beam system 110 may inputparameters of an overall milling procedure (e.g., a recipe) via the userinterface described above to cause the dual beam system 110 to depositthe protective layer 208 and/or the fiducial markers 210 according tothe input parameters.

In reference to FIGS. 2B and 2C, the process 201 may include utilizingthe focused ion beam 118 of the dual beam system 110 and using arelatively high beam current with a corresponding relatively large beamsize to mill relatively large amounts of material away from a frontportion and a back portion of the region of interest 207 to form twomilled trenches 212 and 214. In some embodiments, the two milledtrenches 212 and 214 may have a generally rectangular prism shape. Inother embodiments, the two milled trenches 212 and 214 may havegenerally triangular prism shapes among others. Regardless, remainingmaterial between the two milled trenches 212 and 214 may form a thin, atleast substantially vertical, sample section, i.e., a portion of theinitial lamella 218, which includes the region of interest 207. In someembodiments, the angle of the focused ion beam 118 used in the millingis generally angled at 90° from the upper surface 204 of the wafer 200.This allows for the focused ion beam 118 to mill vertically into wafer200. In other embodiments, the focused ion beam 118 may be oriented at a45 degree angle from a vertical access and may be utilized to formtriangular prism trenches. In one or more embodiments, forming theinitial lamella 218 may not include any cleaning actions and/or thinningprocesses, which are known and conventionally performed in the art. Inother words, the initial lamella 218 may be left intentionally thick. Inother embodiments, forming the initial lamella 218 may include cleaningactions, but the initial lamella 218 may still be left intentionallythick. In some embodiments, an operator of the dual beam system 110 mayinput parameters of the overall milling procedure (e.g., a recipe) viathe user interface to cause the dual beam system 110 to mill thetrenches 212 and 214 according to the input parameters.

Referring to FIG. 2D, after the two milled trenches 212 and 214 areformed, the wafer 200 and the X-Y stage 125 may be tilted and/or rotatedand the dual beam system 110 may make a cut 220 at an angle partiallyalong the perimeter of the initial lamella 218 utilizing the focused ionbeam 118 and leaving the initial lamella 218 hanging by tabs at eitherside at a top of the lamella. In some embodiments, the cut 220 maycreate an asymmetrical lamella. For instance, the asymmetrical lamellamay have a convex quadrilateral shape with one straight side 222 and oneobtuse side 224. More specifically, the initial lamella 218 may be aright trapezoid with two parallel sides. For example, the initiallamella 218 may have the shape depicted in FIG. 2G (described below). Asa non-limiting example, the initial lamella 218 may include any of theasymmetrical lamellae described in U.S. Pat. No. 8,884,247, to Miller etal., issued Nov. 11, 2014. As is known in the art, asymmetrical lamellaemay assist in identifying regions of interest more readily and quickly.In other embodiments, the cut 220 may have a general U-shape and maycreate a general symmetrical lamella. In view of the foregoing, one ofordinary skill in the art will recognize that the initial lamella 218may be formed via any manner known in the art absent cleaning processesand/or thinning process. For instance, the initial lamella 218 may beformed via any of the manners described in U.S. Pat. No. 8,884,247, toMiller et al. In some embodiments, an operator of the dual beam system110 may input parameters of the overall milling procedure (e.g., arecipe) via the user interface to cause the dual beam system 110 to makethe cut 220 according to the input parameters.

In reference to FIG. 2E, prior to and/or after making the cut 220 in theinitial lamella 218, the process 201 may include creating a nest 226near the milling site of the initial lamella 218. For instance, the dualbeam system 110 may utilize either the focused ion beam 118 or theelectron beam 143 along with the gas delivery system 146 to deposit anest 226 adjacent to the milling site of the initial lamella 218 on anupper surface 204 of the wafer 200. For instance, the dual beam system110 may deposit the nest 226 via any of the manners described above inregard to depositing materials utilizing the gas delivery system 146. Insome embodiments, the nest 226 may be sized and shaped to receive anupper portion 202 (i.e., a rectangular portion) of the initial lamella218, as is described in greater detail below. For instance, the nest 226may have a general U-shape. In some embodiments, the nest 226 mayinclude a carbon material (e.g., graphite and/or amorphous carbon). Inother embodiments, the nest 226 may include one or more of tungsten andtetraethyl orthosilicate (“TEOS”). In one or more embodiments, the nest226 may have a U-shape or a right-angle shape. In additionalembodiments, then nest 226 may include a relatively flat layer ofmaterial. As will be described in greater detail below, the nest 226 mayserve to break an electrostatic connection between a probe (e.g., thinprobe 150) and the initial lamella 218. In some embodiments, an operatorof the dual beam system 110 may input parameters of the overall millingprocedure (e.g., a recipe) via the user interface to cause the dual beamsystem 110 to create the nest 226 according to the input parameters. Inother embodiments, the process 201 may not include creating and/ordepositing a nest 226 near the milling site of the initial lamella 218.For example, not every embodiment described herein requires creatingand/or depositing of the nest 226.

Referring to FIGS. 2F-2H, after forming the nest 226 on the uppersurface 204 of the wafer 200, the process 201 may include cutting thetabs (which is known in the art), lifting (e.g., plucking, removing,etc.) the initial lamella 218 from the two milled trenches 212 and 214,and placing (e.g., disposing) the initial lamella 218 on the uppersurface 204 of the wafer 200 proximate the nest 226 on the upper surface204 of the wafer 200. In particular, FIG. 2F represents an action oflifting the initial lamella 218 from the wafer 200 with probe 228. FIG.2G is a front view of the initial lamella 218. FIG. 2H represent anaction of placing the initial lamella 218 back on the upper surface 204of the wafer 200.

Referring to FIGS. 2F-2H together, the initial lamella 218 may be placedon the upper surface 204 of the wafer 200 unlike conventional processes,which typically include placing wafers on a grid. In some embodiments,the process 201 may include lifting and placing the initial lamella 218with a probe 228, which, as noted above, may include probe 150. Forinstance, the process 201 may include lifting and placing the initiallamella 218 with a glass probe. In one or more embodiments, the process201 may include lifting and placing the initial lamella 218 with alamella extraction station (e.g., the micromanipulator 147). In someembodiments, the lamella extraction station may include a TEMLink™ TEMlamella extraction station. For instance, the lamella extraction stationmay include a semi-automated full wafer TEM lamella lift out system.Although a specific system is identified for lifting and placing theinitial lamella 218, the disclosure is not so limited; rather, anysystem known in the art for lifting (i.e., removing) and placing lamellamay be utilized in the process 201. Also, as noted above, in someembodiments, the lamella extraction station may be a part of the dualbeam system 110; and in other embodiments, the lamella extractionstation may be separate from the dual beam system 110 but may beutilized in conjunction with the dual beam system 110.

In view of the foregoing, in some embodiments, the initial lamella 218may be lifted from the wafer 200 and placed (e.g., disposed) back on theupper surface 204 of the wafer 200 outside of the dual beam system 110.For example, after the initial lamella 218 is formed, the wafer 200 maybe unloaded from the dual beam system 110 and the lamella extractionstation may be utilized to lift and place the initial lamella 218external to the dual beam system 110. In other embodiments, the initiallamella 218 may be lifted from the wafer 200 and placed back on theupper surface 204 of the wafer 200 within the dual beam system 110. Forinstance, the lamella extraction station may form an integral part ofthe dual beam system 110 and may lift and place the initial lamella 218within the dual beam system 110 without unloading the wafer 200.

In particular, the process 201 may include lifting the initial lamella218 by positioning the probe 228 over and proximate to the initiallamella 218 and lowering and/or moving a probe tip 230 of the probe 228into contact with the initial lamella 218. In some embodiments, theprobe 150 may utilize electrostatic forces to attract the initiallamella 218 to the probe tip 230 and to grasp the initial lamella 218.In additional embodiments, the probe 150 may have a hollow center, andthe probe 150 may utilize a vacuum created within the hollow center ofthe probe 150 to secure the initial lamella 218 to the probe tip 230.

Referring to FIGS. 2H and 2I together, upon securing the initial lamella218 to the probe tip 230 of the probe 150, the process 201 may includelowering the probe 150 until the initial lamella 218 is placed on theupper surface 204 of the wafer 200 proximate to the nest 226 on theupper surface 204 of the wafer 200. For instance, the initial lamella218 may be laid flat on the upper surface 204 of the wafer 200. As notedabove, in some embodiments, the nest 226 may assist in breaking anelectrostatic connection between the probe 150 and the initial lamella218.

In one or more embodiments, the process 201 may include placing theinitial lamella 218 on the upper surface 204 of the wafer 200 at alocation proximate to the nest 226 and then sliding the initial lamella218 along the upper surface 204 of the wafer 200 into the nest 226. Forinstance, the process may include utilizing the probe 150 to slide theinitial lamella 218 up against the nest 226 until the nest 226 at leastsubstantially surrounds an outer periphery of the upper portion 202 ofthe initial lamella 218. For instance, the process 201 may includealigning the initial lamella 218 within the nest 226. In otherembodiments, the probe 150 may place the initial lamella 218 directlyinto the nest 226 such that the nest 226 at least substantiallysurrounds an outer periphery of the upper portion 202 of the initiallamella 218.

In some embodiments, disposing the initial lamella 218 directly into thenest 226 and/or sliding the initial lamella 218 may result in theinitial lamella 218 not being aligned within the nest 226. For instance,the initial lamella 218 may be askew within the nest 226 and/or thefocusing ion beam 118 (which is used to mill additional lamella(described below)) of the dual beam system 110. Accordingly, in one ormore embodiments, the process may include adjusting and/or reorientingthe initial lamella 218 with the probe 150 to properly align the initiallamella 218 and to ensure that the features of interest included withinthe upper portion 202 of the initial lamella 218 are included within theplanar lamella (described below). In some instances, the initial lamella218 may be adjusted and/or reoriented automatically by one or more ofthe lamella extraction station and the dual beam system 110. Forinstance, the position of the initial lamella 218 may be adjusted toalign internal structures (i.e., the features of interest) within theupper portion 202 of the initial lamella with the focused ion beam 118of the dual beam system 110. As is described in greater detail below inregard to FIGS. 4A-4E, in one or more embodiments, a window (e.g.,milled out portion, a thinned portion, etc.) may be formed in theinitial lamella 218 to expose internal structures (e.g., crystallinestructures) of the initial lamella 218, and the internal structures maybe utilized to align the initial lamella 218. In additional embodiments,the initial lamella 218 may be aligned on the upper surface 204 of thewafer 200 utilizing a tab formed in the nest 226 and a correspondingnotch cut into a top of the initial lamella 218. In particular, the tabof the nest 226 may be inserted into the notch of the initial lamella218 to align the initial lamella with the focused ion beam 118 of thedual beam system 110. In yet further embodiments, the initial lamella218 may be aligned on the upper surface 204 of the wafer 200 utilizing arecess milled into the wafer 200. For instance, the recess may be formedin the shape of an outer peripheral edge of the initial lamella 218, andthe initial lamella 218 may be placed within the recess to align theinitial lamella with the focused ion beam 118 of the dual beam system110.

Referring to FIGS. 2F-2I together, in one or more embodiments, as notedabove, the initial lamella 218, which is milled from the wafer 200, mayinclude the upper portion 202 and a bulk silicon base portion 206.Furthermore, the upper portion 202 may be at a top of the initiallamella 218. As also noted above the upper portion 202 may includefeatures (e.g., internal structures, crystalline structures, etc.) ofinterest, and STEM images of those features may be desirable todetermine a quality of the wafer 200, defects in the wafer 200, etc.Furthermore, as shown in FIG. 2I, in some embodiments, the upper portion202 of the initial lamella 218 may be disposed against the nest 226.Moreover, as will be discussed in greater detail below, the upperportion 202 of the initial lamella 218 may be a targeted portion increating a second lamella.

In embodiments where the wafer 200 is unloaded from the dual beam system110, after placing the initial lamella 218 within the nest 226, theprocess 201 may include reloading the wafer 200 into the dual beamsystem 110. Furthermore, in reference to FIG. 2J, the process 201 mayinclude depositing a material 232 to adhere the initial lamella 218 tothe upper surface 204 of the wafer 200 and at least substantially holdthe initial lamella 218 in place. In some embodiments, the material 232may include tungsten, carbon, and/or TEOS. In one or more embodiments,the material 232 may be deposited utilizing the gas delivery system 146of the dual beam system 110. Additionally, the process 201 may includedepositing one or more fiducial markers 234 proximate to the initiallamella 218 and identifying an additional milling site on the wafer 200.As is known in the art, the fiducial markers 234 may be utilized by thedual beam system 110 for future processing (e.g., milling of a secondlamella). For instance, the fiducial markers 234 may assist the dualbeam system 110 in orienting and moving (e.g., scanning) the focused ionbeam 118. The fiducial markers 234 may be deposited via the gas deliverysystem 146 of the dual beam system 110. In some embodiments, an operatorof the dual beam system 110 may input parameters of an overalladditional milling procedure (e.g., an additional recipe) via the userinterface described above to cause the dual beam system 110 to depositthe material 232 and/or the fiducial markers 234 according to the inputparameters of the additional milling procedure.

After the fiducial markers 234 have been deposited, with reference toFIG. 2K, the process 201 may include milling a second lamella (referredto hereinafter as the “planar lamella 238”) to include at least aportion of the upper portion 202 of the initial lamella 218.Furthermore, the planar lamella 238 may be milled via any of the mannersdescribed above in regard to FIGS. 2A-2D. In some embodiments, anoperator of the dual beam system 110 may input parameters of the overalladditional milling procedure (e.g., an additional recipe) via the userinterface described above to cause the dual beam system 110 to mill theplanar lamella 238 according to the input parameters of the additionalmilling procedure.

Referring to FIG. 2L, in some embodiments, milling the planar lamella238 may further include thinning the planar lamella 238 with the focusedion beam 118. For instance, the dual beam system 110 may thin the planarlamella 238 utilizing the focused ion beam 118. As a non-limitingexample, the planar lamella 238 may be thinned via any of the mannersknown in the art. Furthermore, milling the planar lamella 238 may,optionally, include any cleaning processes known in the art. In someembodiments, an operator of the dual beam system 110 may inputparameters of the overall additional milling procedure (e.g., anadditional recipe) via the user interface described above to cause thedual beam system 110 to thin the planar lamella 238 according to theinput parameters of the additional milling procedure.

In reference to FIGS. 2M and 2N, after milling the planar lamella 238,the process 201 may include lifting the planar lamella 238 from thesecond milling site and placing the planar lamella 238 on an amorphouscarbon grid 240 for imaging with a TEM and/or STEM. For example, theprocess 201 may include lifting the planar lamella 238 via any of themethods described above in regard to FIG. 2F. Furthermore, the process201 may include placing the planar lamella 238 on the amorphous carbongrid 240 via any of the methods described above in regard to FIG. 2H. Aswill be understood in the art, the amorphous carbon grid 240 may assistin breaking any electrostatic connection between the probe 150 and theplanar lamella 238.

After placing the planar lamella 238 on the amorphous carbon grid 240,the process 201 may include imaging and performing metrology on theplanar lamella 238 via TEM and/or STEM systems. For instance, theprocess 201 may include performing automated imaging and metrologyutilizing a Thermo Scientific Metrios™ system. Although specific TEM andSTEM imaging/metrology systems are described herein, the disclosure isnot so limited, and the process 201 may include imaging and/orperforming metrology analysis via any TEM and/or STEM system known inthe art.

FIG. 3 shows an example image obtained via STEM imaging that includesthe upper portion 202 of the initial lamella 218 along with a respectiveupper portion 252 of the planar lamella 238. As shown, because theinitial lamella 218 was milled, placed on its side on the upper surface204 of the wafer 200, milled again as a portion of the planar lamella238, and then placed on the amorphous grid, when the planar lamella 238and, specifically, the portion of the planar lamella 238 including theupper portion 202 of the initial lamella 218 is imaged, a planarcross-section view of the initial lamella 218 is achieved that is notachievable utilizing conventional operations of the dual beam system110. For instance, the planar lamella 238 includes a firstcross-sectional view of internal structures 246 of the wafer 200 withinthe portion of the planar lamella 238 not comprised of the initiallamella 218, and a second cross-sectional view of the internalstructures 246 that is orthogonal to the first cross-sectional viewwithin the portion of the planar lamella 238 comprising the initiallamella 218. The first cross-sectional view may include a view depictinginternal structures 246 as if viewed from a plane orthogonal to theupper surface 204 of the wafer 200, and the second cross-sectional viewmay include a view depicting internal structures 246 as if viewed from aplane parallel to the upper surface 204 of the wafer 200. Conventionalmethods utilizing the dual beam system 110 only achieve the firstcross-sectional view.

Furthermore, because the process 201 described herein provides both thefirst cross-sectional view and the second cross-sectional view, theprocess 201 may provide more complete images of the internal structuresof the wafer 200 in comparison to conventional methods only include thefirst cross-sectional view. As a result, the process 201 may providemore complete information regarding the internal structures of the wafer200. Accordingly, a more complete analysis can be achieved utilizing theprocess 201 described herein in comparison to conventional processes.Due to the more complete analysis, a quality of the wafer 200 anddevices formed thereon may be better determined, which results in betterproducts and more flaws detected.

FIGS. 4A-4E represent an additional process 401 that can be utilized inconjunction with the process 201 described above to align the initiallamella 218 on the upper surface 204 of the wafer 200 and for subsequentmilling. In some embodiments, the process 401 can take place afterdepositing the material 232 over the initial lamella 218. Referring toFIGS. 4A-4C together, which show the initial lamella 218 disposed withinthe nest 226, in some embodiments, the process 401 may include milling awindow 244 within the initial lamella 218. As used herein, the term“window” may include a recess formed within the lamella and exposinginternal structures of the lamella. Furthermore, the window 244 may bemilled utilizing the focused ion beam 118 of the dual beam system 110via any of the methods described above in regard to FIGS. 1-2N. In someinstances, the milling the window 244 may include milling the window 244at least partially within (e.g., to include at least a portion of) theupper portion 202 of the initial lamella 218. Milling the window 244within the upper portion 202 of the initial lamella 218 may expose theinternal structures 246 (e.g., features of interest) of the initiallamella 218. As will be appreciated by one of ordinary skill in the art,in some embodiments, the internal structures 246 may be orientedrelative to one another in at least substantially parallel lines.

Accordingly, once the window 244 in milled within the initial lamella218, the process 401 may include determining if the internal structures246 are oriented as desired relative to the wafer 200, the nest 226,and/or a desired planar lamella 238 thickness and placement (referred toas “248” within FIG. 4B). In some embodiments, the internal structures246 of the initial lamella 218 may need to be aligned with the focusingion beam 118 to achieve an optimal image of the later-to-be-formedplanar lamella 238. In other words, the internal structures 246 and/orthe orientation of the internal structures 246 need to form azero-degree angle with a direction in which the focusing ion beam 118translates (e.g., moves). In some embodiments, the dual beam system 110may utilize pattern recognition and edge finding software to determinethe positions and orientations of the internal structures 246, and as aresult, the overall initial lamella 218 on the upper surface 204 of thewafer 200. For instance, the dual beam system 110 may utilize patternrecognition and edge finding software to determine the position of theinternal structures and as a result, the initial lamella 218, in each ofthe three axes (X, Y, and Z). Additionally, based on the determinedlocations and orientations of the internal structures 246 and initiallamella 218, the dual beam system 110 determines an amount of rotationneeded in each of the three axes to properly align the initial lamellawith the focused ion beam 118 of the dual beam system 110. Furthermore,based on the determined amount of rotation, the dual beam system 110and/or operator may utilize the micromanipulator 147 to rotate theinitial lamella 218 to achieve proper alignment with the focused ionbeam 118 of the dual beam system 110. In other embodiments, the initiallamella 218 may be left as is, and the focusing ion beam 118 can berotated instead to align the focusing ion beam 118 with the internalstructures 246. As will be described in greater detail below, in someembodiments, the dual beam system 110 may further utilize patternrecognition and edge finding software to determine a location of thebulk silicon base portion 206 of the initial lamella 218 within theY-axis to utilize in forming an additional window in the bulk siliconbase portion 206.

Referring to FIGS. 4C and 4D together, once the initial lamella 218 isproperly oriented, the process 401 may include depositing one or morefiducial markers 234 relative to the initial lamella 218 via any of themethods described above in regard to FIG. 2A. In some embodiments,placement of the fiducial markers 234 may be determined based onlocation of the internal structures 246 within the Y-axis, determinedabove in regard to FIGS. 4A and 4B. Furthermore, the process 401 mayinclude milling the planar lamella 238 via any of the methods describedabove in regard to FIG. 2K. Moreover, referring to FIG. 4E, the process401 may include thinning the planar lamella 238 via any of the methodsdescribed above in regard to FIG. 2L. However, the process 401 mayfurther include forming an additional window 250 within the bulk siliconportion of the initial lamella 218 within the planar lamella 238. Forinstance, in typical processes, the planar lamella 238 may be thinnedabout a central longitudinal axis of the upper portion 202 of theinitial lamella 218 in order to ensure that the planar lamella 238includes the features of interest included within the upper portion 202of the initial lamella 218. However, according to the process 401, aportion of the planar lamella 238 may be thinned about an axis extendingthrough the bulk silicon base portion 206 of the initial lamella 218(i.e., the region of the initial lamella 218 below the upper portion202) to form the additional window 250 such that, when thinned, the bulksilicon is exposed on both lateral sides of the planar lamella 238within the additional window 250.

In some embodiments, the additional window 250 within the bulk siliconbase portion 206 of the initial lamella 218 within the planar lamella238 may assist in aligning the planar lamella 238 with TEM beams of theTEM and/or STEM imaging systems described above. For instance, the TEMand/or STEM system may utilize the pattern recognition and edge findersoftware described above to determine a lattice structure of the bulksilicon base portion 206 of the initial lamella 218 and may correctlyalign the planar lamella 238 with respect to the electron beam (forimaging). In some embodiments, the TEM and/or STEM system analyzes adiffraction pattern of the lattice structure of the bulk silicon baseportion 206 within the additional window 250 and determines, based onthe foregoing analysis, required tilts (e.g., α and β tilts) to centerthe pattern of the lattice structure about a zone axis. Creating theadditional window 250 in the bulk silicon base portion 206 of theinitial lamella 218 provides advantages over conventional methods. Forinstance, lamellae milled via conventional methods do not include theadditional window because the lamellae do not include any portion of aninitial lamella. As a result, the diffraction pattern of the latticestructure of the bulk silicon cannot be used to align the lamellae. Aswill be understood by one of ordinary skill in the art, the planarlamella 238 may be lifted, placed, and imaged via any of the methodsdescribed above in regard to FIGS. 2M, 2N, and 3.

FIG. 5 shows a front view of a planar lamella 238 formed via process 201and process 401. As shown, the planar lamella 238 may include the upperportion 202 of the initial lamella 218 providing a planar view of thefeatures of interest (e.g., internal structures) of the wafer 200. Theplanar lamella 238 may further include the additional window 250 formedin the bulk silicon base portion 206 of the initial wafer 200. Theplanar lamella 238 may also include a respective upper portion 252 belowthe initial lamella 218 including features of interest of the wafer 200that can be view from an angle orthogonal to the planar view of theinitial wafer 200. Additionally, the planar lamella 238 may include therespective bulk silicon base portion 254.

FIGS. 6A-6J show a process 601 through which a planar view STEM imagemay be acquired utilizing the dual beam system 110 described above inregard to FIG. 1. In particular, FIGS. 6A-6N show a process 601 foracquiring a planar view STEM image of a lamella having tall features ofinterest (e.g., tall internal structures) that are typically outside ofa usable range for a conventional dual beam system 110.

The process 601 may include forming an initial relatively deep lamella618 (referred to hereinafter as an “initial deep lamella 618”) via anyof the processes described above in regard to FIGS. 2A-2D. For example,the process 601 may include forming an initial deep lamella 618 having adepth within a range of about 4 μm and about 6 μm. Furthermore, theinitial deep lamella 618 may have a relatively thick upper portion 602of features of interest (e.g., tall internal structures). For instance,the upper portion 602 may have a thickness within a range of about 2 μmand about 3 μm. Furthermore, the initial deep lamella 618 may be leftintentionally thick.

In reference to FIG. 6A, the process 601 may include creating a nest 626near the milling site of the initial deep lamella 618. As describedabove in regard to FIG. 2E, the dual beam system 110 may utilize eitherthe focused ion beam 118 or the electron beam 143 along with the gasdelivery system 146 to deposit a nest 626 adjacent to the milling siteof the initial deep lamella 618 on an upper surface 604 of the wafer600. For instance, the dual beam system 110 may deposit the nest 626 viaany of the manners described above in regard to depositing materialsutilizing the gas delivery system 146. In some embodiments, the nest 626may be sized and shaped to receive the upper portion 602 (i.e., arectangular portion) of the initial deep lamella 618, as is described ingreater detail below. For instance, the nest 626 may have a generalU-shape or a right-angle shape. In some embodiments, the nest 626 mayinclude any of the materials described above in regard to FIG. 2E. Inadditional embodiments, the nest 626 may include a relatively flat layerof material. Also, as described above, the nest 626 may serve to breakan electrostatic connection between a probe (e.g., thin probe 150) andthe initial deep lamella 618. Furthermore, as described above, anoperator of the dual beam system 110 may input parameters of the overallmilling procedure (e.g., a recipe) via the user interface to cause thedual beam system 110 to create the nest 626 according to the inputparameters. In other embodiments, the process 601 may not includecreating and/or depositing a nest 626 near the milling site of theinitial deep lamella 618. For example, not every embodiment describedherein requires creating and/or depositing of the nest 626.

Referring to FIGS. 6B-6D, after forming the nest 626 on the uppersurface 604 of the wafer 600, the process 601 may include cutting thetabs, lifting (e.g., plucking, removing, etc.) the initial deep lamella618 from the two milled trenches 612 and 614, and placing (e.g.,disposing) the initial deep lamella 618 on the upper surface 604 of thewafer 600 proximate the nest 626 on the upper surface 604 of the wafer600. In particular, FIG. 6B represents an action of lifting the initialdeep lamella 618 from the wafer 600 with probe 228. FIG. 6C is a frontview of the initial deep lamella 618. FIG. 6D represent an action ofplacing the initial deep lamella 618 back on the upper surface 604 ofthe wafer 600.

The initial deep lamella 618 may be placed on the upper surface 604 ofthe wafer 600 unlike conventional processes, which typically includeplacing wafers on a grid. In some embodiments, the process 601 mayinclude lifting and placing the initial deep lamella 618 with a probe228, which may include probe 150. For instance, the process 601 mayinclude lifting and placing the initial deep lamella 618 with a glassprobe. In one or more embodiments, the process 601 may include liftingand placing the initial deep lamella 618 with a lamella extractionstation (e.g., the micromanipulator 147). In some embodiments, thelamella extraction station may include a TEMLink™ TEM lamella extractionstation. For instance, the lamella extraction station may include asemi-automated full wafer TEM lamella lift out system. Although aspecific system is identified for lifting and placing the initial deeplamella 618, the disclosure is not so limited; rather, any system knownin the art for lifting (i.e., removing) and placing lamella may beutilized in the process 601. Also, as noted above, in some embodiments,the lamella extraction station may be a part of the dual beam system110; and in other embodiments, the lamella extraction station may beseparate from the dual beam system 110 but may be utilized inconjunction with the dual beam system 110.

In view of the foregoing, in some embodiments, the initial deep lamella618 may be lifted from the wafer 600 and placed (e.g., disposed) back onthe upper surface 604 of the wafer 600 outside of the dual beam system110. For example, after the initial lamella 618 is formed, the wafer 600may be unloaded from the dual beam system 110 and the lamella extractionstation may be utilized to lift and place the initial deep lamella 618external to the dual beam system 110. In other embodiments, the initialdeep lamella 618 may be lifted from the wafer 600 and placed back on theupper surface 604 of the wafer 600 within the dual beam system 110. Forinstance, the lamella extraction station may form an integral part ofthe dual beam system 110 and may lift and place the initial deep lamella618 within the dual beam system 110 without unloading the wafer 600.

In particular, the process 601 may include lifting the initial deeplamella 618 by positioning the probe 228 over and proximate to theinitial deep lamella 618 and lowering and/or moving a probe tip 230 ofthe probe 228 into contact with the initial deep lamella 618. In someembodiments, the probe 228 may utilize electrostatic forces to attractthe initial deep lamella 618 to the probe tip 230 and to grasp theinitial deep lamella 618. In additional embodiments, the probe 228 mayhave a hollow center, and the probe 228 may utilize a vacuum createdwithin the hollow center of the probe 228 to secure the initial deeplamella 618 to the probe tip 230.

Referring to FIGS. 6D and 6E together, upon securing the initial deeplamella 618 to the probe tip 230 of the probe 228, the process 201 mayinclude lowering the probe 228 until the initial deep lamella 618 isplaced on the upper surface 604 of the wafer 600 proximate to the nest626 on the upper surface 604 of the wafer 600. For instance, the initialdeep lamella 618 may be laid flat on the upper surface 604 of the wafer600. As noted above, in some embodiments, the nest 626 may assist inbreaking an electrostatic connection between the probe 228 and theinitial deep lamella 618.

In one or more embodiments, the process 601 may include placing theinitial deep lamella 618 on the upper surface 604 of the wafer 600 at alocation proximate to the nest 626 and then sliding the initial deeplamella 618 along the upper surface 604 of the wafer 600 into the nest626. For instance, the process may include utilizing the probe 228 toslide the initial deep lamella 618 up against the nest 626 until thenest 626 at least substantially surrounds at least a portion of an outerperiphery of the upper portion 602 of the initial deep lamella 618. Forinstance, the process 601 may include aligning the initial deep lamella618 within the nest 626. In other embodiments, the probe 228 may placethe initial deep lamella 618 directly into the nest 626 such that thenest 626 at least substantially surrounds an outer periphery of theupper portion 602 of the initial deep lamella 618.

In some embodiments, disposing the initial deep lamella 618 directlyinto the nest 626 and/or sliding the initial deep lamella 618 may resultin the initial deep lamella 618 not being aligned within the nest 226.For instance, the initial deep lamella 618 may be askew within the nest626 and/or the focusing ion beam 118 (which is used to mill additionallamella (described below)) of the dual beam system 110. Accordingly, inone or more embodiments, the process may include adjusting and/orreorienting the initial deep lamella 618 with the probe 228 to properlyalign the initial deep lamella 618 and to ensure that the features ofinterest included within the upper portion 602 of the initial deeplamella 618 are included within a planar second wide, shallow, and thinlamella (described below) (referred to hereinafter as a “planar shallowlamella”. In some instances, the initial deep lamella 618 may beadjusted and/or reoriented automatically by one or more of the lamellaextraction station and the dual beam system 110. For instance, theposition of the initial deep lamella 618 may be adjusted to align thetall internal structures (i.e., the tall features of interest) withinthe upper portion 602 of the initial lamella with the focused ion beam118 of the dual beam system 110. As is described in greater detail belowin regard to FIGS. 8A-8D, in one or more embodiments, a relatively largewindow (e.g., milled out portion, a thinned portion, etc.) may be formedin the initial deep lamella 618 to expose the tall internal structures646 (e.g., crystalline structures) of the initial deep lamella 618, andthe tall internal structures 646 may be utilized to align the initialdeep lamella 618. In additional embodiments, the initial deep lamella618 may be aligned via any of the manners described above in regard toFIGS. 2H, 2I, and 4A-4E.

Referring to FIGS. 6B-6D together, in one or more embodiments, as notedabove, the initial deep lamella 618, which is milled from the wafer 600,may include the upper portion 602 and a bulk silicon base portion 606.Furthermore, the upper portion 602 may be at a top of the initial deeplamella 618. As also noted above the upper portion 602 may include thetall features (e.g., tall internal structures 646, crystallinestructures, etc.) of interest, and STEM images of those tall featuresmay be desirable to determine a quality of the wafer 600, defects in thewafer 600, etc. Furthermore, as shown in FIG. 6E, in some embodiments,the upper portion 602 of the initial deep lamella 618 may be disposedagainst or proximate to the nest 626. Moreover, as will be discussed ingreater detail below, the upper portion 602 of the initial deep lamella618 may be a targeted portion in creating a second lamella (i.e., theplanar shallow lamella).

In embodiments where the wafer 600 is unloaded from the dual beam system110, after placing the initial deep lamella 618 within the nest 626, theprocess 601 may include reloading the wafer 600 into the dual beamsystem 110. Furthermore, in reference to FIG. 6F, the process 601 mayinclude depositing a material 632 to adhere the initial deep lamella 618to the upper surface 604 of the wafer 600 and at least substantiallyhold the initial deep lamella 618 in place. In some embodiments, thematerial 632 may include tungsten, carbon, and/or TEOS. In one or moreembodiments, the material 632 may be deposited utilizing the gasdelivery system 146 of the dual beam system 110. In one or moreembodiments, the material 632 may be disposed in an elongated shape(e.g., an elongated rectangle) having a longitudinal axis at leastsubstantially parallel to longitudinal axes of the features of interestwithin the initial deep lamella 618. For instance, the longitudinal axisof the elongated shape of material 632 may be at least substantiallyperpendicular to an original top surface of the upper portion 602 of theinitial deep lamella.

Additionally, the process 601 may include depositing one or morefiducial markers 634 proximate to and/or on the initial deep lamella 618and identifying an additional milling site on the wafer 600. As is knownin the art, the fiducial markers 634 may be utilized by the dual beamsystem 110 for future processing (e.g., milling of a second lamella).For instance, the fiducial markers 634 may assist the dual beam system110 in orienting and moving (e.g., scanning) the focused ion beam 118.The fiducial markers 634 may be deposited via the gas delivery system146 of the dual beam system 110. In some embodiments, an operator of thedual beam system 110 may input parameters of an overall additionalmilling procedure (e.g., an additional recipe) via the user interfacedescribed above to cause the dual beam system 110 to deposit thematerial 632 and/or the fiducial markers 634 according to the inputparameters of the additional milling procedure.

In one or more embodiments, the one or more fiducial markers 634 may bedeposited proximate longitudinal ends of the elongated shape of material632. As a result, a first fiducial marker 634 may be deposited on theupper surface 604 of the wafer 600 on a side of the nest 626 oppositethe initial deep lamella 618. Additionally, a second fiducial marker 634may be deposited on a lateral side surface of a portion of the initialdeep lamella 618 (e.g., on the bulk silicon base portion 606 of theinitial deep lamella 618). Accordingly, a line extending between thefirst and second fiducial markers 234 may be at least substantiallyparallel to the features of interest within the initial deep lamella 618and perpendicular to a top surface 603 of the upper portion 602 of theinitial deep lamella 618.

After the fiducial markers 634 have been deposited, with reference toFIG. 6G, the process 601 may include milling a second lamella (referredto hereinafter as the “planar shallow lamella 638”) to include at leasta portion of the upper portion 602 of the initial deep lamella 618 andat least a portion of the bulk silicon portion 606 of the initial deeplamella 618. Moreover, the process 601 may include milling the planarshallow lamella 638 to include at least substantially an entire lengthof at least one tall internal structure 646 of the initial deep lamella618. For instance, the planar shallow lamella 638 may be milled suchthat a width (i.e., a lateral width) of the planar shallow lamella 638extends along an original longitudinal length (e.g., an original depth)of the initial deep lamella 618 disposed on the upper surface 604 of thewafer 600. Furthermore, the planar shallow lamella 638 may be milled viaany of the manners described above in regard to FIGS. 2A-2D and 2K. Insome embodiments, an operator of the dual beam system 110 may inputparameters of the overall additional milling procedure (e.g., anadditional recipe) via the user interface described above to cause thedual beam system 110 to mill the planar shallow lamella 638 according tothe input parameters of the additional milling procedure.

Referring to FIG. 6H, in some embodiments, milling the planar shallowlamella 638 may further include thinning the planar shallow lamella 638with the focused ion beam 118. For instance, the dual beam system 110may thin the planar shallow lamella 638 utilizing the focused ion beam118. As a non-limiting example, the planar shallow lamella 638 may bethinned via any of the manners known in the art. Furthermore, millingthe planar shallow lamella 638 may, optionally, include any cleaningprocesses known in the art. In some embodiments, an operator of the dualbeam system 110 may input parameters of the overall additional millingprocedure (e.g., an additional recipe) via the user interface describedabove to cause the dual beam system 110 to thin the planar shallowlamella 638 according to the input parameters of the additional millingprocedure.

In reference to FIGS. 61 and 6J, after milling the planar shallowlamella 638, the process 601 may include lifting the planar shallowlamella 638 from the second milling site and placing the planar shallowlamella 638 on an amorphous carbon grid 640 for imaging with a TEMand/or STEM. For example, the process 601 may include lifting the planarshallow lamella 638 via any of the methods described above in regard toFIGS. 2F and 6B. Furthermore, the process 601 may include placing theplanar shallow lamella 638 on the amorphous carbon grid 640 via any ofthe methods described above in regard to FIGS. 2H and 6D. As will beunderstood in the art, the amorphous carbon grid 640 may assist inbreaking any electrostatic connection between the probe 228 and theplanar shallow lamella 638.

After placing the planar shallow lamella 638 on the amorphous carbongrid 640, the process 601 may include imaging and performing metrologyon the planar shallow lamella 638 via TEM and/or STEM systems. Forinstance, the process 601 may include performing automated imaging andmetrology utilizing a Thermo Scientific Metrios™ system. Althoughspecific TEM and STEM imaging/metrology systems are described herein,the disclosure is not so limited, and the process 601 may includeimaging and/or performing metrology analysis via any TEM and/or STEMsystem known in the art.

FIG. 7 shows an example image obtained via STEM imaging that includesthe upper portion 602 of the initial deep lamella 618 along with arespective upper portion 652 of the planar shallow lamella 638. Asshown, because the initial deep lamella 618 was milled, placed on itsside on the upper surface 604 of the wafer 600, milled again as aportion of the planar shallow lamella 638, and then placed on theamorphous grid, when the planar shallow lamella 638 and, specifically,the portion of the planar shallow lamella 638 including the upperportion 602 of the initial deep lamella 618 is imaged, a planarcross-section view of the initial deep lamella 618 is achieved that isnot achievable utilizing conventional operations of the dual beam system110. For instance, the planar deep lamella 638 includes a firstcross-sectional view of the tall internal structures 646 of the wafer600 within the portion of the planar shallow lamella 638 not comprisedof the initial deep lamella 618, and a second cross-sectional view ofthe tall internal structures 646 that is orthogonal to the firstcross-sectional view within the portion of the planar shallow lamella638 comprising the initial deep lamella 618. The first cross-sectionalview may include a view depicting the tall internal structures 646 as ifviewed from a plane orthogonal to the upper surface 604 of the wafer600, and the second cross-sectional view may include a view depictingthe tall internal structures 646 as if viewed from a plane parallel tothe upper surface 604 of the wafer 600.

Moreover, the process 601 provides a method for creating TEM/STEMlamella of high-aspect ratio samples and having relatively tall internalstructures 646 which are typically outside of a usable range of aconventional dual beam system. Furthermore, because the process 601described herein provides both the first cross-sectional view and thesecond cross-sectional view, the process 201 may provide more completeimages of the tall internal structures 646 of the wafer 600 incomparison to conventional methods only include the firstcross-sectional view. As a result, the process 601 may provide morecomplete information regarding the tall internal structures 646 of thewafer 600. Accordingly, a more complete analysis can be achievedutilizing the process 601 described herein in comparison to conventionalprocesses. Due to the more complete analysis, a quality of the wafer 600and devices formed thereon may be better determined, which results inbetter products and more flaws detected.

FIGS. 8A-8D represent an additional process 801 that can be utilized inconjunction with the process 601 described above to align the initialdeep lamella 618 on the upper surface 604 of the wafer 600 and forsubsequent milling. In some embodiments, the process 801 can take placeafter depositing the material 632 over the initial lamella 618.Referring to FIGS. 8A-8D together, which show the initial deep lamella618 disposed within the nest 626, in some embodiments, the process 801may include milling a window 844 within the initial deep lamella 618.The window 844 may include any of the windows described above in regardto FIGS. 4A-4E. Furthermore, the window 844 may be milled utilizing thefocused ion beam 118 of the dual beam system 110 via any of the methodsdescribed above in regard to FIGS. 1-2N and 4A-4E. In some instances,the milling the window 844 may include milling the window 844 at leastpartially within (e.g., to include at least a portion of) the upperportion 602 of the initial deep lamella 618. Milling the window 844within the upper portion 602 of the initial deep lamella 618 may exposethe tall internal structures 646 (e.g., features of interest) of theinitial deep lamella 618. As will be appreciated by one of ordinaryskill in the art, in some embodiments, the tall internal structures 646may be oriented relative to one another in at least substantiallyparallel lines.

In some embodiments, the window 844 may span at least a majority of awidth of the upper portion 602 of the initial deep lamella 618. Forexample, the window 844 may extend longitudinally in a directionperpendicular to a direction in which the tall internal structure 646extend within the initial deep lamella 618. Furthermore, the window 844may extend over multiple tall internal structures 646.

Accordingly, once the window 844 in milled within the initial lamella618, the process 801 may include determining if the tall internalstructures 646 are oriented as desired relative to the wafer 600, thenest 626, and/or a desired planar shallow lamella 638 thickness andplacement (referred to as “648” within FIGS. 8B and 8C). In someembodiments, the tall internal structures 646 of the initial deeplamella 618 may need to be aligned with the focusing ion beam 118 toachieve an optimal image of the later-to-be-formed planar shallowlamella 638. In other words, the tall internal structures 646 and/or theorientation of the tall internal structures 646 need to form azero-degree angle with a direction in which the focusing ion beam 118translates (e.g., moves). In some embodiments, the dual beam system 110may utilize pattern recognition and edge finding software to determinethe positions and orientations of the tall internal structures 646, andas a result, the position and orientation of the overall initial deeplamella 618 on the upper surface 604 of the wafer 600. For instance, thedual beam system 110 may utilize pattern recognition and edge findingsoftware to determine the position of the tall internal structures 646and as a result, the initial deep lamella 618, in each of the three axes(X, Y, and Z). Additionally, based on the determined locations andorientations of the tall internal structures 646 and initial deeplamella 618, the dual beam system 110 determines an amount of rotationneeded in each of the three axes to properly align the initial deeplamella 618 with the focused ion beam 118 of the dual beam system 110.Furthermore, based on the determined amount of rotation, the dual beamsystem 110 and/or operator may utilize the micromanipulator 147 torotate the initial deep lamella 618 to achieve proper alignment with thefocused ion beam 118 of the dual beam system 110. In other embodiments,the initial deep lamella 618 may be left as is, and the focusing ionbeam 118 can be rotated instead to align the focusing ion beam 118 withthe tall internal structures 646.

In some embodiments, the relatively large size of the window 844 (e.g.,the large size of the window 844 relative to the window 244 describedabove in regard to FIGS. 4A-4E) may enable dual beam system 110 to moreaccurately determine a position and location of the initial deep lamella618 and, as a result, achieve a finer and more accurate rotation of theinitial deep lamella 618. In particular, because of the relatively largesize of the window 844, the window 844 may expose more tall internalstructures 646 in comparison to the window 244 described above in regardto FIGS. 4A-4E. Furthermore, because the tall internal structures 646 ofthe initial deep lamella 618 have a greater length than the internalstructures 246 of the initial lamella 218, a more accurate alignment maybe necessary to ensure that a second lamella (i.e., the planar shallowlamella 638) is properly centered about a tall internal structure 646 ofthe initial deep lamella 618. For instance, because the tall internalstructures 646 of the initial deep lamella 618 are relatively long, anyerror in alignment would be magnified at longitudinal ends of the tallinternal structures 646 and may result in the planar shallow lamella 638not being properly aligned. However, because the window 844 may exposemore tall internal structures 646 in comparison to the window 244, thedual beam system 110 may have more data (i.e., patterns and edges) todetermine a position and location of the initial deep lamella 618 andany required rotations of the initial deep lamella 618.

Referring to FIGS. 8C and 8D together, once the initial deep lamella 618is properly oriented, the process 401 may include depositing one or morefiducial markers 634 relative to the initial deep lamella 618 via any ofthe methods described above in regard to FIGS. 2A and 6F. In someembodiments, placement of the fiducial markers 634 may be determinedbased on location of the tall internal structures 646 within the Y-axis,determined above in regard to FIGS. 8A and 8B. Moreover, the fiducialmarkers 634 may be deposited, and an offset between a center of thefiducial marker 634 and a center longitudinal axis of an internalstructure 64 about which the planar shallow lamella 638 may be milled ismeasured. Furthermore, the process 801 may include milling the planarshallow lamella 638 via any of the methods described above in regard toFIGS. 2K and 6G. Moreover, the process 801 may include thinning theplanar shallow lamella 638 via any of the methods described above inregard to FIG. 2L. In additional embodiments, one or more additionalwindows may be formed in the planar shallow lamella 638 via any of themanners described above in regard to FIG. 4E.

FIG. 9 shows a front view of a planar shallow lamella 638 formed viaprocess 601 and process 801. As shown, the planar shallow lamella 638may include the upper portion 602 of the initial deep lamella 618providing a planar view of the features of interest (e.g., tall internalstructures 646) of the wafer 600. The planar shallow lamella 638 mayfurther include a window 850 formed in the upper portion 602 (i.e.,formed via any of the manners described above in regard to FIG. 4E) andthe bulk silicon base portion 606 of the initial deep lamella 618. Theplanar shallow lamella 638 may also include a respective upper portion652 below the initial deep lamella 618 including features of interest ofthe wafer 600 that can be viewed from an angle orthogonal to the planarview of the initial deep lamella 618. As shown in FIG. 9, the window 850may extend into the upper portion 652 of the planar shall lamella 638.Additionally, the planar shallow lamella 638 may include a respectivebulk silicon base portion 670.

Some embodiments of the present disclosure include a method of preparinga sample. The method may include loading a wafer on a stage, milling aninitial lamella within the wafer using a focused ion beam, lifting theinitial lamella out of the wafer, placing the initial lamella on anupper surface of the wafer on a lateral side of the initial lamella,milling a planar lamella out of a portion of the initial lamella and thewafer beneath the initial lamella, lifting the planar lamella out of thewafer, and placing the planar lamella on a carbon grid.

One or more embodiments of the present disclosure include method ofpreparing a sample. The method may include loading a wafer on a supportsurface, milling an initial lamella within the wafer using a focused ionbeam, lifting the initial lamella out of the wafer, placing the initiallamella on an upper surface of the wafer on a lateral side of theinitial lamella, milling a window within an upper portion of the initiallamella exposing internal structures of the initial lamella, based atleast partially on the exposed internal structures of the initiallamella, aligning the initial lamella on the upper surface of the wafer,milling a planar lamella out of a portion of the initial lamella and thewafer beneath the initial lamella, lifting the planar lamella out of thewafer, and placing the planar lamella on a carbon grid.

Some embodiments of the present disclosure include a method of preparinga sample. The method may include placing a wafer on a support, millingan initial lamella within the wafer using a focused ion beam, liftingthe initial lamella out of the wafer, placing the initial lamella on anupper surface of the wafer on a lateral side of the initial lamella,milling a planar lamella out of a portion of the initial lamella and thewafer beneath the initial lamella, milling a window within a bulksilicon portion of the portion of the initial lamella included withinthe planar lamella, lifting the planar lamella out of the wafer, placingthe planar lamella on a carbon grid and based at least partially on aconfiguration of the window formed in the bulk silicon portion of theportion of the initial lamella included within the planar lamella,aligning the planar lamella with an electron beam of a TEM imagingsystem or a STEM imaging system.

One or more embodiments of the present disclosure include a method ofpreparing a sample. The method may include milling an initial lamellawithin a wafer, lifting the initial lamella out of the wafer, placingthe initial lamella flat on an upper surface of the wafer, and milling aplanar lamella to include at least a portion of the initial lamella.

Some embodiments of the present disclosure include a method of preparinga sample. The method may include disposing a wafer on a surface, millingan initial lamella within the wafer using a focused ion beam, liftingthe initial lamella out of the wafer, placing the initial lamella on anupper surface of the wafer on a lateral side of the initial lamella,milling a window within an upper portion of the initial lamella toexpose internal structures of the initial lamella, based at leastpartially on the exposed internal structures of the initial lamella,aligning the initial lamella on the upper surface of the wafer, millinga planar lamella out of a portion of the initial lamella and the waferbeneath the initial lamella, milling an additional window within a bulksilicon portion of the portion of the initial lamella included withinthe planar lamella, lifting the planar lamella out of the wafer, placingthe planar lamella on a carbon grid, and based at least partially on aconfiguration of the additional window formed in the bulk siliconportion of the portion of the initial lamella included within the planarlamella, aligning the planar lamella with an electron beam of a TEMimaging system or a STEM imaging system.

One or more embodiments of the present disclosure include a method ofpreparing a sample. The method may include milling an initial lamellawithin a wafer using a focused ion beam, the initial lamella comprisinga upper portion and a lower portion, the upper portion comprising aportion of the initial lamella initially proximate to an upper surfaceof the wafer, lifting the initial lamella out of the wafer with alamella extraction station, placing the initial lamella flat on an uppersurface of the wafer with the lamella extraction station, milling aplanar lamella to include at least a portion of the upper portion of theinitial lamella, and imaging the planar lamella via a TEM or STEMimaging system to include imaging of the at least a portion of the upperportion of the initial lamella.

Some embodiments of the present disclosure include a method of preparinga sample. The method may include milling an initial deep lamella withina wafer using a focused ion beam, the initial deep lamella comprising atleast one internal structure within an upper portion of the initial deeplamella, lifting the initial deep lamella out of the wafer, placing theinitial deep lamella on an upper surface of the wafer on a lateral sideof the initial lamella, milling a planar shallow lamella out of aportion of the initial deep lamella and the wafer beneath the initialdeep lamella to include at least substantially an entire length of theat least one internal structure of the initial deep lamella, lifting theplanar shallow lamella out of the wafer; and placing the planar shallowlamella on a carbon grid.

One or more embodiments of the present disclosure include a method ofpreparing a sample. The method may include milling an initial deeplamella within a wafer using a focused ion beam, the initial deeplamella comprising internal structures within an upper portion of theinitial deep lamella, lifting the initial deep lamella out of the wafer,placing the initial deep lamella on an upper surface of the wafer on alateral side of the initial lamella, milling a window within an upperportion of the initial deep lamella exposing multiple internalstructures of the initial deep lamella, based at least partially on theexposed multiple internal structures of the initial deep lamella,aligning the initial deep lamella on the upper surface of the wafer,milling a planar shallow lamella out of a portion of the initial deeplamella and the wafer beneath the initial lamella to include at leastsubstantially an entire length of at least one internal structure of theinternal structures of the initial deep lamella, lifting the planarshallow lamella out of the wafer, and placing the planar shallow lamellaon a carbon grid.

Some embodiments of the present disclosure include a method of preparinga sample. The method may include milling an initial deep lamella withina wafer, lifting the initial deep lamella out of the wafer, placing theinitial deep lamella flat on an upper surface of the wafer, depositingan elongated shape of material over the initial deep lamella, theelongated shape having a longitudinal length being at leastsubstantially perpendicular to a top surface of the initial deeplamella, and milling a planar lamella to include at least a portion ofthe initial lamella.

The embodiments of the disclosure described above and illustrated in theaccompanying drawings do not limit the scope of the disclosure, which isencompassed by the scope of the appended claims and their legalequivalents. Any equivalent embodiments are within the scope of thisdisclosure. Indeed, various modifications of the disclosure, in additionto those shown and described herein, such as alternate usefulcombinations of the elements described, will become apparent to thoseskilled in the art from the description. Such modifications andembodiments also fall within the scope of the appended claims andequivalents.

What is claimed is:
 1. A method of preparing a sample, the methodcomprising: milling an initial deep lamella within a wafer using afocused ion beam, the initial deep lamella comprising at least oneinternal structure within an upper portion of the initial deep lamella;lifting the initial deep lamella out of the wafer; placing the initialdeep lamella on an upper surface of the wafer on a lateral side of theinitial deep lamella; milling a planar shallow lamella out of a portionof the initial deep lamella and the wafer beneath the initial deeplamella to include at least substantially an entire length of the atleast one internal structure of the initial deep lamella; lifting theplanar shallow lamella out of the wafer; and placing the planar shallowlamella on a carbon grid.
 2. The method of claim 1, further comprising:forming a nest on the upper surface of the wafer proximate to a millingsite of the initial deep lamella; and placing the initial deep lamellawithin the nest on the upper surface of the wafer.
 3. The method ofclaim 2, wherein the nest comprises at least one of carbon, tungsten, ortetraethyl orthosilicate.
 4. The method of claim 2, wherein placing theinitial deep lamella with in the nest comprises: placing the initialdeep lamella on the upper surface of the wafer proximate to but outsideof the nest; and sliding the initial deep lamella along the uppersurface of the wafer and into the nest.
 5. The method of claim 1,wherein lifting the initial deep lamella out of the wafer and placingthe initial deep lamella on the upper surface of the wafer are performedutilizing a lamella extraction station external to a dual beam system.6. The method of claim 1, wherein lifting the initial deep lamella outof the wafer comprises lifting the initial deep lamella with a probesecuring the initial deep lamella with an electrostatic connection. 7.The method of claim 1, wherein milling an initial deep lamella withinthe wafer comprises milling an asymmetric initial deep lamella.
 8. Themethod of claim 1, wherein milling a planar shallow lamella out of aportion of the initial deep lamella comprises milling the planar shallowlamella to such that a width of the planar shallow lamella extends alonga longitudinal length of the initial deep lamella.
 9. The method ofclaim 1, further comprising imaging the planar shallow lamella on thecarbon grid via a TEM or STEM imaging system to include imaging of theportion of the initial deep lamella.
 10. A method of preparing a sample,the method comprising: milling an initial deep lamella within a waferusing a focused ion beam, the initial deep lamella comprising internalstructures within an upper portion of the initial deep lamella; liftingthe initial deep lamella out of the wafer; placing the initial deeplamella on an upper surface of the wafer on a lateral side of theinitial deep lamella; milling a window within an upper portion of theinitial deep lamella exposing multiple internal structures of theinitial deep lamella; based at least partially on the exposed multipleinternal structures of the initial deep lamella, aligning the initialdeep lamella on the upper surface of the wafer; milling a planar shallowlamella out of a portion of the initial deep lamella and the waferbeneath the initial deep lamella to include at least substantially anentire length of at least one internal structure of the internalstructures of the initial deep lamella; lifting the planar shallowlamella out of the wafer; and placing the planar shallow lamella on acarbon grid.
 11. The method of claim 10, further comprising depositing amaterial over the initial deep lamella on the upper surface of the waferto secure the wafer prior to milling the planar shallow lamella.
 12. Themethod of claim 11, wherein depositing a material over the initial deeplamella comprises depositing a material as an elongated shape having alongitudinal length being at least substantially perpendicular to a topsurface of the upper portion of the initial deep lamella.
 13. The methodof claim 11, wherein depositing a material over the initial deep lamellacomprises depositing a material as an elongated shape having alongitudinal length being at least substantially parallel to alongitudinal length of the at least one internal structure of theinternal structures of the initial deep lamella.
 14. The method of claim10, further comprising imaging the planar shallow lamella on the carbongrid via a TEM or STEM imaging system to include imaging of the portionof the initial deep lamella.
 15. The method of claim 10, furthercomprising depositing at least one first fiducial marker on the uppersurface of the wafer proximate the initial deep lamella and at least onesecond fiducial marker on a lateral side surface of the initial deeplamella to identify a milling site of the planar shallow lamella andprior to milling the planar shallow lamella.
 16. The method of claim 10,wherein milling a planar shallow lamella out of a portion of the initialdeep lamella comprises thinning the planar shallow lamella and cleaningthe planar shallow lamella.
 17. The method of claim 10, furthercomprising: forming a nest on the upper surface of the wafer proximateto a milling site of the initial deep lamella; placing the initial deeplamella within the nest on the upper surface of the wafer; and based atleast partially on the exposed multiple internal structures of theinitial deep lamella, aligning the initial deep lamella within the nest.18. The method of claim 17, wherein the nest comprises at least one ofcarbon, tungsten, or tetraethyl orthosilicate.
 19. The method of claim17, wherein placing the initial deep lamella with in the nest comprises:placing the initial deep lamella on the upper surface of the waferproximate to but outside of the nest; and sliding the initial deeplamella along the upper surface of the wafer and into the nest.
 20. Amethod of preparing a sample, the method comprising: milling an initialdeep lamella within a wafer; lifting the initial deep lamella out of thewafer; placing the initial deep lamella flat on an upper surface of thewafer; depositing an elongated shape of material over the initial deeplamella, the elongated shape of material having a longitudinal lengthbeing at least substantially perpendicular to a top surface of theinitial deep lamella; and milling a planar lamella to include at least aportion of the initial deep lamella.
 21. The method of claim 20, whereindepositing a material over the initial deep lamella comprises depositinga material as an elongated shape having a longitudinal length being atleast substantially parallel to a longitudinal length of at least oneinternal structure of the initial deep lamella.
 22. The method of claim20, wherein milling a planar lamella comprises milling the planarlamella centered within the elongated shape of material.